Windows 10 legacy printer installation for the HP LaserJet 2100 seems to
have gotten worse recently, according to my experience and that of others,
where Windows Update will no longer even give you a choice of similar
drivers for the HP LJ 2100.
The [Windows Update] button for legacy printers has been dead for weeks
http://alt.comp.os.windows-10.narkive.com/1C8HOEOU/the-windows-update-button-for-legacy-printers-has-been-dead-for-weeks

However, SC Tom and this note below provide a *better* solution than this:
http://alt.comp.os.windows-10.narkive.com/yKNzX4YR/quick-tutorial-for-installing-the-hewlett-packard-hp-laserjet-2100tn-printer-on-windows

It seems that the Windows Update is failing for others who are seeking
drivers for legacy printers based on this report I just read:
April 6, 2018:
Windows 10 Printer Lists - unable to update printer list from Windows Update
https://answers.microsoft.com/en-us/windows/forum/windows_10-hardware/windows-10-printer-lists-unable-to-update-printer/3cad241e-b999-46d2-9515-e1ca628d0ef9

The beauty of this "Windows Catalog" method is that it allows you to
archive the printer drivers as a "cab" file, so you do not have to go
through the "Windows Update" abomination ever again (if you save the cab
files of course).

In summary, the following are useful to note:
1. The "Windows Update" is failing to get *any* driver list lately
2. Even if it did work, it's impossible *save* the driver archive
3. The Windows Catalog method solves both those problems instantly

--
Anyone who suggests DriveBack or DoubleDriver hasn't tried it on printers.
(I wish they'd work on printer drivers - but they just don't.)